Influence of psychological factors on grip strength.

PURPOSE: Grip strength is widely used to assess upper-extremity function. Although grip strength is a quantitative measure of function, grip strength is a reflection of both physical impairment as well as subjective, psychological factors. We investigated the determinants of grip strength with the hypothesis that psychological factors are associated with diminished grip strength.
METHODS: One hundred thirty-four patients with an isolated, discrete upper-extremity condition had grip strength measurements, and, as part of one of several prospective clinical studies, during the same visit they completed 2 or more of the following surveys: the Center for Epidemiologic Studies-Depression (CES-D) scale, Pain Anxiety Symptoms Scale, and Pain Catastrophizing Scale. Univariate and multivariable statistical analysis sought determinants of absolute grip strength and grip strength as a percentage of the opposite, uninvolved limb.
RESULTS: Determinants of absolute grip strength included gender and grip strength of the uninvolved limb. The association between CES-D score and absolute grip strength was near significant but very weak. Multivariable regression analysis produced a best-fit model that retained grip strength of the uninvolved limb and CES-D scores. When grip strength of the involved limb was evaluated as a percentage of grip strength of the uninvolved limb, CES-D score was a weak but significant predictor, and patients recovering from a fracture of the distal radius had weaker grip strength than did patients with nontraumatic conditions.
CONCLUSIONS: Depression scores were minimally associated with diminished grip strength. Psychological factors appear to affect disability (patient-reported health status) more than they affect performance-based measures of function. TYPE OF STUDY/LEVEL OF EVIDENCE: Prognostic II.